Such a type of conventional cylinder device having a force multiplier is disclosed in Patent Literature 1 (Japanese Patent Application Publication, Tokukai, No. 2001-25932 A). The conventional technique is configured as follows:
A main piston is arranged in a right part of a housing, and a sub piston is arranged in a left part of the housing. A cylindrical hole of the sub piston is fitted to a piston rod of the main piston. A lever of a lever-type force multiplier is swingably supported in a space on a left outside of the sub piston. An input section, provided outside in a radial direction of the lever, is in contact with a left surface of an outer circumference part of the sub piston, and an output section, provided inside in the radial direction of the lever, is coupled to the piston rod of the main piston.
By supply of pressurized air into a drive chamber formed between the main piston and the sub piston, the sub piston, which is driven leftward, carries out force multiplication driving rightward with respect to the piston rod (and the main piston) via the lever.
Another type of cylinder device having a force multiplier is disclosed in Patent Literature 2 (Japanese Patent No. 4945681 B, the specification). The conventional technique is configured as follows:
An output rod is inserted in a housing so as to be movable vertically. In an upper part of the housing, a first piston is formed so as to be integrated with a central part in an axis direction of the output rod. A second piston inserted in a lower part of the housing is fitted on a lower half part of the output rod so as to be hermetically movable vertically. A lock chamber is arranged between the first piston and the second piston. A first release chamber is arranged above the first piston, and a second release chamber is arranged below the second piston. A wedge-type force multiplier is arranged in the second release chamber provided below the second piston.